The invention relates to nuclear power systems, and more particularly to grid structures for nuclear reactor fuel assemblies and the like.
The core of a nuclear reactor typically includes a plurality of fuel assemblies arranged in close spaced relationship in an array the periphery of which approximates a cylinder. These fuel assemblies for a nuclear reactor typically include a plurality of elongated fuel rods held in spaced relationship in an array by a plurality of spacer grids.
To load or unload a fuel assembly into or from the reactor core, it is necessary to move the fuel assembly with respect to fuel assemblies adjacent thereto. This relative movement of adjacent fuel assemblies has resulted in the problem of hangup between the spacer grids of the adjacent assemblies. This hangup can occur between the sides of spacer grids of laterally adjacent fuel assemblies or between the corners of spacer grids of diagonally adjacent fuel assemblies. This hangup can result in irreparable damage to spacer grids, fuel rods, and may leave torn away pieces in the core which must be retrieved.
Many attempts have been made in the prior art to solve the problem of handling interaction and strength of fuel assembly spacer grids. The prior art solution to the problem of hangup between diagonally adjacent assemblies at the corners of the spacer grids has been to chamfer the upper and lower corners of the exterior grip strip. This configuration is superior to the unchamfered configuration but does not completely eliminate the possibility of diagonal hangup.